There has conventionally been widely known a hyper text system such as WWW (World Wide Web), which is provided in a network such as Internet and permits to browse various kinds of information sources such as web pages, image data and document data, which are widely scattered on the network through a hyper link (hereinafter simply referred to as the “link”) embedded on a web page having a description using a markup language such as HTML (Hyper Text Markup Language).
In such a hyper text system, a user generally accesses search sites such as for example Google (trademark), Yahoo (trademark), Infoseek (trademark), etc. with the use of a terminal equipment such as a personal computer to retrieve the information source of the web page required by the user from various kinds of information source scattered on the network.
In such search sites, numerous information sources are normally subject to searches with the use of retrieval key words provided by the users. A challenge is therefore to display the retrieved information source as the retrieval result in how priority, so as to access quickly the information source, which is suited to the user's purpose.
In case of Google (trademark), for example, the priority of the web page (or the web site) is set to become higher with the increased number of links provided by the other web sites, and the priority of the above-mentioned web page is set to become higher with the increased priority of the web site providing the links to the above-mentioned web page.
Patent Document 1 discloses a technical matter in which web pages as retrieved based on a retrieval result judgment document are examined in suitability, the web pages are classified into a suitable group and a non-suitable group based on the examination results, there are extracted common words, which appear frequently in the web pages of the suitable group, and common words, which appear frequently in the web pages of the non-suitable group, and a new retrieval operation is taken based on these common words.
Apart from such a method to analyze the web pages, etc., to determine the retrieval priority, there has been known a method to analyze a user's action (instructions to a terminal equipment), after the display of the retrieval result, to determine the priority or narrow the retrieval range.
For example, Patent Document 2 discloses a technical matter in which properties of information acquired by a user are recognized from cookie or an Internet temporary file, and the information suited to such properties is subject to retrieval first and then the retrieval result is outputted.    Patent Document 1: Japanese Patent Provisional Publication No. 2002-215642    Patent Document 2: Japanese Patent Provisional Publication No. 2004-510257